The present invention relates to an electronic camera incorporating an image reflecting mirror in which both still picture and a motion picture photographing operations can be carried out and switched over to each other. More particularly, the invention relates to a changeover device for such a camera.
In an electronic camera, an image pickup device such as a solid state image pickup element provides electrical signals indicative of the brightness of the image of an object being photographed, and these signals are stored on a magnetic disc or in a semiconductor memory. The electronic camera is advantageous in that it uses no film which requires chemical treatment, and the pictures taken by the camera can be reproduced on a television set immediately. A variety of electronic cameras has been proposed to replace conventional cameras which use film.
In the electronic camera, instead of film, an image pickup device is used. However, the essential components of the camera mechanism, such as the exposure control device, that is, components other than the image pickup device, are generally the same as those used in the conventional film camera. That is, the electronic camera achieves exposure operation utilizing a metering device, shutter and lens stop, the same as a still-type film camera.
An electronic camera of course has a lens and image pickup device. If the electronic camera is coupled to a motion picture recording device such as a video tape recorder, it is theoretically possible to use the electronic camera as a video camera.
A viewfinder in such an electronic camera may be single-lens type optical viewfinder with an image reflecting mirror or a half-silvered mirror, a typical example of which is a quick return mirror, or an electronic viewfinder. The optical viewfinder using a quick return mirror is disadvantageous in that it has moving parts; however, it is advantageous in that the viewfinder image is bright and the light beam to the image pickup device is not attenuated by the viewfinder.
In the case where a quick return mirror is used in a video camera in which both motion picture photographing operations and still picture photographing operations can be performed, it is necessary that, in the motion picture photographing operation, the quick return mirror be retracted from the photographing optical path and that the shutter for taking still pictures be fully opened. This condition corresponds to a so-called "bulb photographing condition" in still picture photographing operations as far as the quick return mirror and the shutter are concerned. Motion picture photographing operations are of course different in procedure from still picture bulb photographing, and the mechanism for this purpose must be simple. However, no electronic camera with a quick return mirror capable of both still picture and motion picture photographing operations which can be selectively switched over to each other has been realized as yet.
For instance, in a still picture bulb photographing operation, while the release button is depressed, the mirror is retracted and the shutter is released. In order to use this mechanism for motion picture photographing operations, it is necessary to additionally provide a release button for taking motion pictures or to start the motion picture recording operation simultaneously with the retraction of the mirror. However, the former method is disadvantageous in that the operation is intricate, and the latter method is also disadvantageous in that the recording operation cannot be carried out when desired.
In the case where, in addition to the still picture bulb photographing mechanism, a mirror retracting mechanism and a shutter releasing mechanism are provided, the mechanisms themselves are intricate. If these mechanisms are not operated simultaneously for motion picture photographing operations, the shutter will be released during nonphotographing periods, and hence a high intensity light beam may reach the image pickup element, damaging the latter.